1. Field of the Invention
This invention relates to an application or pressing station for foil sheets placed around the neck and the top of bottles. The application or pressing station has a transport star wheel that rotates around a first axis of rotation. The transport star wheel has receptacles located on its circumference for receiving the bottles. The station includes application or pressing elements that can be lowered onto the tops of the bottles and are positioned on the circumference of a support located above the transport star wheel. The support rotates around a second axis of rotation that is offset in relation to the first axis of rotation. The orbits of the receptacles on the transport star wheel and the application or pressing elements are synchronized with one another over a section of the station positioned between the bottle entrance and exit of the transport star wheel, where the application or pressing elements are lowered.
2. Background Information
Application stations of this type may form part of a labelling machine in which the bottles are held and transported in a turntable where foil sheets are applied. One problem with such labelling machines is that collisions may occur during the transfer of the bottles from the turntable into the transport star wheel, when it performs the function of a discharge star wheel. That is because the orbits of the centering heads that act on the bottle tops on the turntable, and the application or pressing elements that act on the bottle tops in the discharge star wheel, overlap in the transfer region between the turntable and the discharge star wheel. To obtain optimal synchronization during the application of the foil sheets, special precautions must be taken in the control and design of the application or pressing elements, if there is a lowerable application or pressing element above each receptacle, to avoid a collision between the centering heads and the application or pressing elements in the transfer region between the turntable and the discharge star wheel.
German Patent No. 31 04 807 C2, discloses a label application or pressing station in which precautions have been taken to avoid such collisions. These precautions include pivoting each application or pressing element to the side from its position above the receptacle, into a position which lies outside the area passed over by the centering head of the turntable. Only when the application or pressing element has passed the transfer region, between the turntable and the discharge star wheel, is it pivoted over the bottle top of the corresponding receptacle and lowered for the application or pressing of the foil sheet. Disadvantages of such an application or pressing station are that a great deal of space is required for the pivoting movement and the drive and transmission that create the pivoting and subsequent lowering movements. Therefore, complex and expensive equipment is required.
These disadvantages associated with the pivoting movement are not present with another application or pressing station described in German Patent No. 33 45 228 A1. In that station, the application or pressing elements are non-pivotally mounted on the circumference of a support. The support has a smaller diameter than, and is mounted off-center in relation to, the discharge star wheel in such a way that the orbit of the application or pressing elements remains outside of the orbit of the receptacles on the turntable. The orbit of the application or pressing elements approximately coincides with the orbit of the receptacles of the feeder star wheel along only on a small segment between the bottle entrance of the discharge star wheel and the exit of the discharge star wheel. In comparison to the first application or pressing station described above, this application or pressing station has the disadvantage that only approximate synchronization can be achieved over the above-mentioned segment. As long as this application or pressing station is operated below the maximum possible capacity, that deviation from absolute synchronization is not critical.
German Patent No. G 85 12 906.2 discloses a foil application or pressing station in which the orbit of the application or pressing elements that are mounted on a support is also smaller than the orbit of the receptacles of the discharge star wheel. Also, the center of the orbit is off-center in relation to the orbit of the receptacles of the discharge star wheel to achieve synchronization in the area in which the application or pressing elements are lowered. The otherwise circular orbit of the receptacles is displaced by the corresponding bottle guide. That bottle guide includes a stationary guide rail against which the bottles are flexibly braced by rubber cushions and are pressed into the receptacles. During the rotation of the discharge star wheel, the bottles are moved radially. That movement results in a significant load on the bottles that is, however, acceptable at low production rates.
One common element found in all of the above described application or pressing stations is that for the required lowering movement of the application or pressing elements, the elements are movably mounted in a support and a cam drive is provided for each application or pressing element. Therefore, the cost of equipment for the lowering devices of the application or pressing elements is significant. Additionally, because of that guidance system for the application or pressing elements and their drive mechanisms, the area above the discharge star wheel is almost completely occupied by equipment.
On such pressing stations, the rotating paths of the delivery positions of the turntable and of the delivery star wheel overlap, so that the bottles can be transferred in synchronization from the turntable to the delivery star wheel. Since during transport of the bottles both in the turntable and in the delivery star wheel, elements such as centering heads grip the tops of the bottles when the bottles are on the turntable and pressing elements grip the tops of the bottles when the bottles are on the delivery star wheel, it is difficult to achieve a collision-free fit of the elements of the turntable and of the delivery star wheel in the overlapping region. Also, for purposes of transferring the bottles from the turntable to the delivery star wheel at the proper angle of rotation, the bottles in the turntable must be held as long as possible in a rotation-free manner by axial bracing between the turntable which supports the bottom of the bottle, and the centering element which grips the top. For a collision-free passage of the pressing elements of the delivery star wheel, it is necessary to move the pressing elements out of the overlapping area during the passage.
In German Laid Open Patent Appln. No. 31 04 807 C2, which corresponds to U.S. Pat. No. 4,414,056, this problem is approached by equipping each pressing element so that it can pivot to one side from its position above the receiving position, into a position which lies outside the portion of the turntable traversed by the centering head of the turntable. Only when the pressing element has passed the overlapping area can it be pivoted over the bottle top of the corresponding receiving position, and then lowered to press the foil sheet. One disadvantage of such pressing stations is that a great deal of space is required for the pivoting movement, and the drive and transmission mechanisms required for the pivoting motion and the subsequent axial movement are quite complex and expensive.
These disadvantages related to the pivoting movement do not occur on another pressing station disclosed in German Laid Open Patent No. 35 15 730 A1. In that patent, the pressing elements are located so that they pivot on the circumference of a support, that has a smaller diameter than that of the delivery star wheel, and is mismatched in relation to the delivery star wheel. With that configuration, the path of the pressing elements lies outside the path of the receiving positions of the turntable and only above a short segment of the path of the receiving positions of the delivery star wheel. A disadvantage, however, is that synchronization between the receiving positions of the delivery star wheel and the pressing elements can only be achieved over the above-mentioned short segment, and then only approximately, which has a negative effect on the quality of the pressing of the foil sheet.
On the pressing stations described above, however, a collision-free passage of the pressing elements on the delivery star wheel and the centering heads on the turntable or synchronization between the receiving positions of the delivery star wheel and the pressing elements is only guaranteed during operation when there is no jamming up at the outlet of the delivery star wheel. To prevent major damage to the pressing station when there is a jamming up at the outlet of the delivery star wheel, the delivery star wheel is coupled with the drive by means of a slip clutch. If a jamming up does occur, then the delivery star wheel can slip in relation to the drive. That configuration requires pivotable pressing elements which are oriented concentrically to the receiving positions causing the synchronization between the turntable and the pressing elements is lost. When rotation continues, therefore, even with the pressing elements pivoted back, collisions may occur. In another pressing station of the prior art described above, with the support for the pressing elements offset and not torsionally connected to the delivery star wheel, a slipping of the delivery star wheel in relation to the drive as a result of a jam leads to an offset between the receiving positions and the pressing elements corresponding to the receiving positions in the pressing area. Once again, the result is that the pressing elements can no longer be placed centrally over the bottle tops.